The present invention relates to original readers and an optical reading method and, more particularly, to an original reader and an optical reading method, which are used for facsimile units, digital copiers, scanners, etc., and serves to optically read out letters and/or drawing data from an original with scanning by a module 1, which includes a light source, a contracting optical system and a CCD as integral constituents, and convert the read-out data to electric signal.
With rapid development of communication techniques of facsimile units or the like and data processing techniques mainly concerning personal computers, has made it necessary to read out letters and/or drawing data from an original and transfer the read-out data with the above facsimile unit or input the data to a data processing unit such as a personal computer. The original reader is an input means to this end.
In such original reader, part of letters and/or drawings is optically read out usually by using a sensor including a photo-sensitive device such as a linear CCD (charge-coupled device) array, and shift of relative positions of the sensor and the original, i.e., scanning, is caused. It is thus usual to read out two-dimensional letters and/or drawing data from an original by conversion to electric signals. As for the relative shift, i.e., scanning, between the sensor and original, in the case of the facsimile unit the original is shifted by a mechanical drive means. In the case of the scanner or the like, the original is held stationary on an original support table while causing the sensor shift.
Prior art of such original readers is disclosed in various literatures. As an example, an image reader is disclosed, which comprises a first carriage having a mirror for receiving light from a scanning surface and a second carriage having two mirrors for receiving light from the first carriage mirror and forming a light path up to a CCD. The image reader further comprises a bearing holder with a bearing secured thereto such as to be in contact with the second carriage being shifted in the scanning direction, a mirror holder, and a reinforcing member for reinforcing the bearing holder and the mirror holder. The image reader thus can quickly read out high quality images free from swaying or deviation (see Literature 1: Japanese Laid-open 2000-253209).
Another image reader is also disclosed, in which a motor, a speed change gear, a synchromesh pulley and a slider are disposed on a scanner holder, and also an image sensor unit is disposed on the holder by means of a spring. In this image reader, the reliability of the scanning of the scanner for reading is held suitably (see Literature 2: Japanese Laid-open 2001-77983). Furthermore, a reflector mounting arrangement for an image reader is disclosed. In this arrangement, a carriage with an optical unit assembled therein has an also assembled reinforcing member, with a reflector tied thereto. Thus, the operability of assembling the reflector and the mounting accuracy are improved (see Literature 3: Japanese Laid-open 2003-295342).
However, the above prior art original readers have problems that the stability, reading accuracy and size and weight reduction are insufficient.